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MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nayna , Mimi Zohar , David Howells , keyrings@vger.kernel.org, Paul Mackerras , Alexander Gordeev , Rob Herring , Herbert Xu , Baoquan He , Christian Borntraeger , James Morris , Lakshmi Ramasubramanian , Christian Borntraeger , "Serge E. Hallyn" , Vasily Gorbik , linux-s390@vger.kernel.org, Heiko Carstens , linux-crypto@vger.kernel.org, Hari Bathini , Daniel Axtens , Dmitry Kasatkin , Frank van der Linden , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Luis Chamberlain , Sven Schnelle , linux-security-module@vger.kernel.org, Jessica Yu , linux-integrity@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, "David S. Miller" , Thiago Jung Bauermann , buendgen@de.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Michal, On Thu, 25 Nov 2021 19:02:44 +0100 Michal Suchanek wrote: > Multiple users of mod_check_sig check for the marker, then call > mod_check_sig, extract signature length, and remove the signature. > > Put this code in one place together with mod_check_sig. > > Signed-off-by: Michal Suchanek > --- > include/linux/module_signature.h | 1 + > kernel/module_signature.c | 56 ++++++++++++++++++++++++++++- > kernel/module_signing.c | 26 +++----------- > security/integrity/ima/ima_modsig.c | 22 ++---------- > 4 files changed, 63 insertions(+), 42 deletions(-) > > diff --git a/include/linux/module_signature.h b/include/linux/module_signature.h > index 7eb4b00381ac..1343879b72b3 100644 > --- a/include/linux/module_signature.h > +++ b/include/linux/module_signature.h > @@ -42,5 +42,6 @@ struct module_signature { > > int mod_check_sig(const struct module_signature *ms, size_t file_len, > const char *name); > +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name); > > #endif /* _LINUX_MODULE_SIGNATURE_H */ > diff --git a/kernel/module_signature.c b/kernel/module_signature.c > index 00132d12487c..784b40575ee4 100644 > --- a/kernel/module_signature.c > +++ b/kernel/module_signature.c > @@ -8,14 +8,36 @@ > > #include > #include > +#include > #include > #include > > +/** > + * mod_check_sig_marker - check that the given data has signature marker at the end > + * > + * @data: Data with appended signature > + * @len: Length of data. Signature marker length is subtracted on success. > + */ > +static inline int mod_check_sig_marker(const void *data, size_t *len) I personally don't like it when a function has a "check" in it's name as it doesn't describe what the function is checking for. For me mod_has_sig_marker is much more precise. I would use that instead. Thanks Philipp > +{ > + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > + > + if (markerlen > *len) > + return -ENODATA; > + > + if (memcmp(data + *len - markerlen, MODULE_SIG_STRING, > + markerlen)) > + return -ENODATA; > + > + *len -= markerlen; > + return 0; > +} > + > /** > * mod_check_sig - check that the given signature is sane > * > * @ms: Signature to check. > - * @file_len: Size of the file to which @ms is appended. > + * @file_len: Size of the file to which @ms is appended (without the marker). > * @name: What is being checked. Used for error messages. > */ > int mod_check_sig(const struct module_signature *ms, size_t file_len, > @@ -44,3 +66,35 @@ int mod_check_sig(const struct module_signature *ms, size_t file_len, > > return 0; > } > + > +/** > + * mod_parse_sig - check that the given signature is sane and determine signature length > + * > + * @data: Data with appended signature. > + * @len: Length of data. Signature and marker length is subtracted on success. > + * @sig_len: Length of signature. Filled on success. > + * @name: What is being checked. Used for error messages. > + */ > +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name) > +{ > + const struct module_signature *sig; > + int rc; > + > + rc = mod_check_sig_marker(data, len); > + if (rc) > + return rc; > + > + if (*len < sizeof(*sig)) > + return -ENODATA; > + > + sig = (const struct module_signature *)(data + (*len - sizeof(*sig))); > + > + rc = mod_check_sig(sig, *len, name); > + if (rc) > + return rc; > + > + *sig_len = be32_to_cpu(sig->sig_len); > + *len -= *sig_len + sizeof(*sig); > + > + return 0; > +} > diff --git a/kernel/module_signing.c b/kernel/module_signing.c > index cef72a6f6b5d..02bbca90f467 100644 > --- a/kernel/module_signing.c > +++ b/kernel/module_signing.c > @@ -25,35 +25,17 @@ int verify_appended_signature(const void *data, size_t *len, > struct key *trusted_keys, > enum key_being_used_for purpose) > { > - const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > struct module_signature ms; > - size_t sig_len, modlen = *len; > + size_t sig_len; > int ret; > > - pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], modlen); > + pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], *len); > > - if (markerlen > modlen) > - return -ENODATA; > - > - if (memcmp(data + modlen - markerlen, MODULE_SIG_STRING, > - markerlen)) > - return -ENODATA; > - modlen -= markerlen; > - > - if (modlen <= sizeof(ms)) > - return -EBADMSG; > - > - memcpy(&ms, data + (modlen - sizeof(ms)), sizeof(ms)); > - > - ret = mod_check_sig(&ms, modlen, key_being_used_for[purpose]); > + ret = mod_parse_sig(data, len, &sig_len, key_being_used_for[purpose]); > if (ret) > return ret; > > - sig_len = be32_to_cpu(ms.sig_len); > - modlen -= sig_len + sizeof(ms); > - *len = modlen; > - > - return verify_pkcs7_signature(data, modlen, data + modlen, sig_len, > + return verify_pkcs7_signature(data, *len, data + *len, sig_len, > trusted_keys, > purpose, > NULL, NULL); > diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c > index fb25723c65bc..46917eb37fd8 100644 > --- a/security/integrity/ima/ima_modsig.c > +++ b/security/integrity/ima/ima_modsig.c > @@ -37,33 +37,17 @@ struct modsig { > * > * Return: 0 on success, error code otherwise. > */ > -int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len, > +int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t len, > struct modsig **modsig) > { > - const size_t marker_len = strlen(MODULE_SIG_STRING); > - const struct module_signature *sig; > struct modsig *hdr; > - size_t sig_len; > - const void *p; > + size_t sig_len, buf_len = len; > int rc; > > - if (buf_len <= marker_len + sizeof(*sig)) > - return -ENOENT; > - > - p = buf + buf_len - marker_len; > - if (memcmp(p, MODULE_SIG_STRING, marker_len)) > - return -ENOENT; > - > - buf_len -= marker_len; > - sig = (const struct module_signature *)(p - sizeof(*sig)); > - > - rc = mod_check_sig(sig, buf_len, func_tokens[func]); > + rc = mod_parse_sig(buf, &buf_len, &sig_len, func_tokens[func]); > if (rc) > return rc; > > - sig_len = be32_to_cpu(sig->sig_len); > - buf_len -= sig_len + sizeof(*sig); > - > /* Allocate sig_len additional bytes to hold the raw PKCS#7 data. */ > hdr = kzalloc(sizeof(*hdr) + sig_len, GFP_KERNEL); > if (!hdr)